Taper snap switch



May 20, 1947- J. H. SCHELLMAMy 2,420,913

TAPER SNAP SWITCH Filed 4Sept.. 27, 1943 4 Sheets-Sheet 1 May 20, 1947.J. H. sci-lELLMm TAPER SNAP SWITCH Filed Sept. 27, 1943 4 Sheets-Sheet 2@ge/wig n .2 w ,j A o Y A W & m

May 20, 1947- J.'H. scHELLMAN '2,420,913

' TAPER SNAP SWITCH Filed Sept. 27. 1943, 4 Sheets-Sheet 3 May 20,1'947- J. H. SCHELLMAN 2,420,913

' TAVPER SNAP .SWITCH Filed Sept. 27, 1943 4 Sheets-Sheet 4 f, lim

, A-n- YL- aiented ay 20,

TAPER SNAP SWITCH lloseph H. Schellman, Ridley Park, Pa., assigner toRobert Hetherington & Son, Inc., Wilmington, Dei., a corporation ofDelaware y Application September 27, 1943, Serial No. 503,876

My invention relates to a snap switch of the hill and valley type inwhich a shorting bar is snapped by a hill and valley plunger from openposition in which the shorting bar or shuttle is disconnected from thecontact terminals to a position in which the shorting bar closes acircuit or closes circuits, and in which the plunger may or may not bespring retracted.

A main purpose of the invention is to secure a very small, compact,reliable snap switch capable of carrying fairly highcurrents.

A further purpose is to provide a hill and valley plunger type of snapswitch in which the slopes of the tapers on the plunger are different,providing for over-travel in one direction of movement and for a quickbreak of the circuit in the opposite direction.

A further purpose is to throw the shorting bar or shuttle of a hill andvalley type snap switch by separate transverse operating springs heldwithin the bar or shuttle by means effective at the ends of the springs.

A further purpose is to provide a shorting bar or shuttle for a hill andvalley type snap switch in which opposite, transverse springs effectingthe movement of the bar are anchored at their ends to theends of thebar.

A further purpose is to adapt my switch construction to either normallyopen or normally closed switch construction by merely reversing thedirection of shorting bar contact parts and reversing the position ofthe contacts to be made by them.

A further purpose is to facilitate assemblage' of transverse springs ina shorting bar for a hill and valley type switch by dropping the springsinto the' shorting bar laterally and holding them in by closures of thelateral space at the sides of the ends of the springs.

A further purpose is to hold springs which are transverse to the plungerof a hill and valley type switch in position by side contact with theends. of the springs, determining the resistance to plunger travelby thedistance and closeness with which the -ends of the springs are connedwithin the shorting bar, permitting the 'same structure to be used forswitches having different plunger operating pressures by making a slightadjustment. A further purpose is to ground the shorting bar of a hilland valley type plunger switch so that two circuits maybe handled by theswitch, be it normally open or normally closed.

A further purpose is to form a shorting bar of a hill and valley typeplunger switch of a contact 4 Claims. (Cl. 20D- 76) 2 plate turnedtransversely to form the ends of the bar and of a second platepermissibly of insulation held in place by its engagement with the endsof the shorting bar.

Further purposes will appear in the specification and in the claims.

I have preferred to illustrate a few forms only y among many which aresuitable for my purpose, selecting forms which are practical, effective,reliable and inexpensive and which at the same time well illustrate theprinciples of my invention. V

Figure 1 is a perspective view of one form of the invention.

modified form of the snorting bar structure of Figure 6.

Figure 8 is a section of Figure 7 taken between the springs, parallel tothem and perpendicular to the frontv contact plate.

Figure 9 is a section of Figure 8 taken on line 9 9.

Figure 10 is e section correspondinggenerally with Figure 2 but showinga second desirable form,

Figures 11 and l2 are sections taken length-v wise through an operatingbutton and a plunger showing variant forms. v

Figure 13 is an axial sectionof a sleeve showing a form differing fromthatv seen in Figures 2 and 10 and suited to a two-circuit groundingswitch.

Figure 14 is a diagrammatic view shovvingtwo circuits to be grounded.

Figure 15- is a perspective View of a modified i form of the invention.

Figures 16 and 17 are axial sections taken lat,

right angles to each other showingthe structure.v

of Figure 10.

Figure 18 is a transverse-section of Fiigurueil'iy taken upon linesl1-`-I1. Figure 19 is a perspective of. a rnodifiedior` the snorting baror shuttle seenin\1 -igure..6 v.l.

'further .generally with Figure 6.

. Figure 25 is section showing the way in which any of my switches, withor without grounded plunger, can be made normally closed instead ofnormally open. by merely turning the shorting bar upside down andputting the contacts below the shorting bar.

The present invention relates particularly to snorting bar or shuttlemechanism and to the associated taper or plunger and other switchstructure for use with hill-and-valley switches. In these switches aspring-retracted plunger carries a double operating taper engaged byinwardly pressing springs within a shuttle. The springs react uponopposite faces of the double wedge or taper on the plunger, each taperface in turn carrying the springs, and hence their associated shuttle,down the slope of the wedge after the hump or crest of the plunger wedgeor taper shall have been pushed-or tretracted-past the springs. Byreason of the double (wedge) taper carried by the plunger this plungerin its entirety is also called a taper. i

The structures of Figures 1 to 9 and 15 to 24 are single-throw switcheswhich use the shuttle `or shorting bar to bridge across between contactsrepresenting the opposite sides of the same switch gap. As a result, acircuit is opened and closed at two places. 'I'he structure of Figures10-14 closes or opens a gap and grounds the circuits on opposite sidesof the gap at the same time each at one point only. The switch is ofsingle-throw type.

It makes no difference in this action whether the shorting bar close thecircuit byupward movement or be turned upside down as in Figure 25 tonormally close the circuit at the lower end of itsA stroke.

Describing the structure of Figure 1 to Figures 6 and 24, the casing 25represents any suitable tubular casing. It may be metallic andelectrically conducting if desired, so that it may be grounded andafford a ground for switch parts as in Figures 10-14. It is shown asseparately or additionally insulated from the switch contacts to be"closed in any event. The exterior of this casing is nished at 26 andflanged at 21 for mounting purposes. The milled grooves 28 are forkeycuits and is retracted forwardly to open the circuit or circuits.

Within thespace 35- a generally cylindrical in'- sulating sleeve orshell 36 protects the circuit contacts. The spring presses against aclosed usually insulating (but in- Figures 10-14 electricallyconducting) end 31 of the sleeve and compresses against it. T-he sleeveis a tight enough *it within the casing to stay in its place and may Y 4be placed accurately in its position by engagement with a shoulder 38.

The plunger or taper 39 is xed rigidly at 40 within the insulatingbutton and at its opposite (rear) end 4| is guided to slide withinrecess 42 in insulation block 43. A plate 44 insulates the rear edges ofthe casing. The insulation 43 carries a rib 45 projecting across therear of the structure.

Electrical terminals 46 and 41 are threaded into the insulation block 43and at their front ends are transversely turned to form terminalcontacts 48 and 49, or 48', 49' (Figure 25). At their outer threadedends they receive nuts 5 6 against which outside circuit contact is madeby conductors 5 I, 5 I held in position by nuts 52 and washers 53. l

kThe plunger or taper carries conical wedge faces 54 and 55, oppositelyconverging from bases at the crest 56. The rear wedge face 55 is ofsteeper slope than the front face 54. This provides for rapid switchbreaking movement of the shorting bar or shuttle with slower switchclosing movement and overtravel in the direction oi! closing movement. f

About the plunger is located a snorting bar, A

messenger or shuttle comprising a front plate-51, a. rear plate 58,connected to form a channel 59 between the two plates. The shuttlecarries an electrically conducting annulus at its iront face 60 which isto connect across from one inwardly turned contact bar to the other.

The front plate andthe rear plate are connected by ends 6l, 62, bentrearwardly from the end ledges of the front plate 51 and cooperatingwith the rear plate 58 to hold the rear plate in position. The bent ends6I, 62 can intert variously with the rear plate.

In the particular form shown the lateral edges of the ends are notchedat v63 to receive projections 64, 65 from the sides of the rearpreferably insulating plate 58 so that when the rear plate is inposition and the ends of the front plate are bent rearwardly as seen inFigure 6, the notches in the ends receive the projections. The frontplate ends lock the rear plate laterally by the projections 64, 65 andrearwardly by the parts 66 of the bent ends adjacent the notches.

Movement of the rear plate forwardly is' prevented by lateial ears 61,66 which are cut free from the ends at 69 and which in the blank beforebending extend out farther laterally than the parts 66 of the ends.

The plunger or taper 39 moves through the openings 10, 1i in the frontand rear plates, respectively, and between two generally parallel-spriral springs 12, 13 which are held so as to press against thetapered surfaces of the plunger in order that with plunger movement theymay react to carry the shorting bar or shuttle .forwardly when'theplunger moves rearwardly and rearwardly when the plunges movesforwardly.

The generally parallel lengths of spiral springs 12 and 13 are retainedwithin the groove of the snorting bar by means shown diierently in thevarious figures. In Figures 1 to 6 these spiral springs are heldin placeby the ears 61, 68, which limit the laterally outward movements of theends of the springs and leave a predetermined intermediate length ofeach spiral spring which,

subject to the support of the ends by the ears,

'may bulge through the spac'e 14 between the ends of facing ears.

The generally parallel spiral springs may .be

not pressing against the inner faces of the ends of the bar, or mayengage the inside faces of the ends -of the bar adjacent the attachedends of the ears. In assembly the springs may be put in position withinthe shorting bar as the ends 6|, 62 are being turned rearwardly orbefore they are turned rearwardly.

The ears 61, 68 may be bent inwardly from the endswhen the sheet metalfrom which the front plate and ends are cut is being blanked out, or canquite obviously be bent inwardly after the ends have been bent down. Ineither case they can be placed so'as properly to hold the springs inposition. The rear plate is put into position as the ends or at least asone end is being bent rearwardly.

As will be seen in Figure 6, the extent to which the ears from the sameend are bent inwardly toward each other will determine the amount oflaterally against it are used to furnish the impulse for the operationof the vshorting bar. These springs are stretched lengthwise and arefastened at their ends 'l'l to the ends of the shorting bar so yas topress laterally against one or other of the oppositely facing plungerwedge faces.

In this form as in the first form shown one transverse face of theshorting bar must be electrically conducting and for this reason is madea metal front plate. kThough metal would be entirely suitable for therear plate of the bar here also in the normally closed circut formtherear plate lis preferably made of insulating material which is quitestiff enough for the purpose but is much less expensive and much lessscarce.

In Figure'? the rear plate is held at the rear by ears 18 pressed out ofthe ends of the front plate.

In Figure 10 an axial section corresponds generally with Figure 2 butshows a different form suited for grounding two circuits through theplunger.

The sleeve is in two parts. The cylindrical part of the sleeve is madeof molded insulating material seen at 36' and the end 3l' is no longerinsulating but is a separate part, an electrical conductor, a force twithin the electricall'iv grounded metal casing. It is intended to makeelectrical contact at its outer circumference with the inside of thecasing and at an intermediate position with the retraction spring 34'.The retraction spring connects electrically with the plunger 39' throughthe electrically conducting button 32'. The plunger engages transverseshorting bar springs, shorting bar front plate and the separatecontacts, which are the terminals to be grounded.

flat strips, interlocking with the insulation block- 43'. They aremolded into the insulation block and are laterally turned at their frontends. They are provided with apertured ends 8l in order that theconnecting conductors leading to and from their circuits may be passedthrough these openings and soldered to the terminals.'

In Figure 10 the metal button is cast about a case-hardened steel taper,the boss 82-of the taper or plunger being encased in the metal of thebutton. In Figure 12 another way of fastening a chrome plated plunger isshown in that 'the boss 82' is a forced fit within an opening 83 in themetal button and the lower end of sleeve 84 is peened about the flange85 to-hold the parts together. 'I'he plunger may be case hardened andthe several parts may be brass plated or chrome plated or otherwisetreated or coated as desired.

In Figure 11 a structure closely similar to that in Figure 10 isshown'in that the button is molded about a case-hardened steel taper. orplunger; differing from the button 32 and plunger construction of Figure10 and from the button 322 ofl'Figure 12 323 is of insulating materialand is made of molding compound.

In Figure 13 a separate view is shown ci the cylindrical insulatedsleeve and'the separat(x metallic front end of the sleeve. The metaliciront end may be forced into the casing so as to make good electricalcontact with the inside of the casing, using a shoulder 38 to limit itsposition as in the case of the front end of the sleeve in Figure 2. Theange 44' serves the purpose of the plate 44.

Figure 14 is a diagrammatic view illustrating the short circuiting ofthe two laterally turned ,terminals 48 and 49 by the plunger so as toclose and open two circuits at one point each, groundton electricallyconnected to the plunger.

The separate electrically conducting end for I I the insulating sleeveis flanged at 19 in order that The omission of the retracting springrequires that the plunger be moved by hand or by power in bothdirections of stroke. Asl shown, it is intended to be hand operated bybutton 324.

The-outer part of the casing is threaded at 86 and the electricalconductors are molded into the insulation block. 'I'he same general formof shorting bar is seen asin Figure 'l except that the ends of the.generally parallel operating springs are fastened to ribs 31 leftbetween slits 88-cut in the rearwardly turned ends -of the shortingbar.-

In Figures 20, 21, 22 and 23 another form is shown which is operated bya cam lever and which is retained in closed switch position by the .theswitch casing is omitted. The camlever 89 is pivoted at 90 and throws acam face 9| .from the open switch position seen in Figure 21 to theclosed switch position seen in Figure 22. The

l movement effected by the cam is communicated to the plunger through acylindrical guide 92 which carries boss 93 which is surrounded by theretracting spring. The plunger is seated in the boss or in thecylindrical guide 92 or in both and the operation of the plunger andshorting bar are the'same as in Figures 2 and 10.

In operation, in Figures .2 and 16, the button is pushed against theresistance of the retraction spring, the limit of movement beingconveniently s et either by the bottom of the press-button engaging thefront of the sleeve or by the bottom of the plunger engaging the bottomofI the recess in which the plunger operates. The transverse spiralsprings have considerable lateral play` but they are held securelyagainst undue lateral movement and furthermore are thus held to theirduty to give reliable retracting pressure to the plunger,

The shorting bar cannot move downwardly in Figure 2 because ofengagement of the edges 15 at instead of being flanged to iit within thesleeve, and may be electrically conducting for the grounded plungerform.

In Figure 25 the use of a plate 312 as the front end of the sleeve 362permits either metal or insulation to be used for this front end as 4preferred, the metal accommodating use with a of the ends with theinsulation block and so the plunger moves through the springs stretchingthem laterally until the crest 56 of the double wedge passes the middleparts of the springs at which time the contraction of the springs causesthe shorting bar to shift forwardly along the length of the plunger anduntil thefront plate of the shorting bar engages and cross connects thecontact parts of the terminals d8 and I9. This closes the circuitbetween the Acontact at 48 and the front plate of the shorting bar andagain beween the front plate of the shorting bar and the contact 49.

In the form of Figure 10, grounding of the plunger through theretraction spring, metal end of the sleeve and casing results ingrounding the shorting bar at all times and two circuits are closedthrough the two contacts 48' and 49' and ground.

In the forms of Figures 16, 17 and 21, 22, special operating mechanismis shown but the principles of operation are the same.

It will be evident that whether the electrically conducting front end'of the sleeve (31') being extended inwardly or not will depend upon.the amount of clearance between it and the contacts 48', 49', sincethis must not be short circuited. It does not make any difference in thenormally closed form of this switch since thecontacts will be below(using the directions of Figure 10) the shorting bar. In the normallyclosed form (of the type of Figure 25) the extended edges 15 of theshorting bar will face upwardly and will use the front end of the sleeveas a step to their travel. 'Ihis will be permissible whether the frontend be electrically conducting or insulating since the shorting bar willbe disconnected from the contacts at the upper end of its stroke. Theform of Figure 25 is. therefore, suitable for grounded plunger-andtherefore grounded circuit through the plunger-use.

In Figure 25 the front end of the sleeve is made grounded plunger toground the circuits and the insulation iitting in with the other forms.The contacts Maand 492 may be connected with any type of terminals andare intended of course to be diagrammatic only.

Having thus described my invention, what I claim as new and desire toprotect by Letters Patent is:

1. A shorting bar for a. hill and valley switch comprising an aperturedfront contact plate, a rear insulating plate, connections between thetwo plates,'substantially parallel spiral springs lying between the twoplates, and ears connected with the :front plate and restraining theouter sides of the ends of the springs to limit lateral distortion ofthe springs.

2. A shorting bar for a hill and valley switch comprising an aperturedfront contact plate, a rear insulating plate, connections between thetwo plates, substantially parallel spiral springs Lying between the' twoplates. and adiustable lateral holding means engaging the sides of theends of the springs, retaining the springs against lateral distortion toan extent depending upon the adjustment of the ears and limiting bulgingof the springs between the ears.y

3. A shorting bar for a hill and valley plunger switch having anelectrically conducting front face apertured for plunger passage, endsrearwardly turned from the front face,` a rear face similarly aperturedinter-fitting with the ends,

ears extending'from the ends, and springs between the two faces held inplace laterally by the'ears and adapted to engage the wedge faces of ahill and valley plunger.

4. In a hill and valley switch, a casing, insulation for the interior ofthe casing, electrical conductors entering the casing and insulated fromit, transverse terminals from said conductors, a shorting bar having`transversely extending springs and an electrically conducting frontplate, a plunger cooperating with the shorting bar and carryingoppositely facing wedge surfaces pressing against the springs, and meansfor holding the springs Within the bar, said means restraining thesprings at their sides near the 'ends of the springs and determining theresistance of the springs to side distortion by the plunger by theextent of restraint given the springs.

JOSEPH H. SCHELLMAN.

REFERENCES CITED The following references are of record in the le ofthis patent:

, UNITED STA'IES PATENTS Number

